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Aero / A-Arm Design

Aero / A-Arm Design

Old 03-20-2014, 07:31 PM
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Default Aero / A-Arm Design

So a discussion of sorts and a question for the community and manufactures.

So in looking at many of the RC Cars on the market and comparing them with 1:1 racing cars. Why hasn't a company spent more time looking at shaping A-Arms with a more Aero efficient shape. or even a shape that provides downforce. (Think about how far a Truggy's arm sticks out) Or diffuser of some sort... I realize that its off-road, but at the same time one could argue that moving the cab forward or back behind a hulking shock tower doesn't make a difference. Additionally covers, or lexan shields for in front of towers to make them less like air brakes, or some other way to mount the shocks. Perhaps under a horizontal surface rather then a vertical system. More like a 1:1 shock mounting.

Just some ideas and ponders because I just don't see to many new things coming out that are going to be game changers.
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Old 03-20-2014, 08:05 PM
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Crazy; I've been thinking about the same thing lately.

Making the front arms to be shaped like an airplane wing to create downforce or upforce...

I ran across a picture recently (can't remember where) with some pieces of lexan mounted to the front arms to create downforce. Kind of going in the same direction here...

That was the first thing I thought when I saw the cab-forward designs, especially ones like the Bitty that has a big window. It would be too easy to place a flat piece of lexan in front of the front shock tower to create the same effect, and then you could just whip out the scissors and tune accordingly.

I'm glad you posted this, though. I am curious to maybe hear other's ideas about the same thing regarding creating downforce in the front.
Originally Posted by Stirex View Post
So a discussion of sorts and a question for the community and manufactures.

So in looking at many of the RC Cars on the market and comparing them with 1:1 racing cars. Why hasn't a company spent more time looking at shaping A-Arms with a more Aero efficient shape. or even a shape that provides downforce. (Think about how far a Truggy's arm sticks out) Or diffuser of some sort... I realize that its off-road, but at the same time one could argue that moving the cab forward or back behind a hulking shock tower doesn't make a difference. Additionally covers, or lexan shields for in front of towers to make them less like air brakes, or some other way to mount the shocks. Perhaps under a horizontal surface rather then a vertical system. More like a 1:1 shock mounting.

Just some ideas and ponders because I just don't see to many new things coming out that are going to be game changers.
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Old 03-20-2014, 08:25 PM
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Old 03-20-2014, 08:57 PM
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That's getting closer to the idea. I have a feeling the top of the arms would have more of an effect. As far as lexan front wings there may be something in ROAR or IF MAR preventing a true front wing. But seems to me there are a lot of aero things that could be improved. Same with cooling scoops for ecars or or electronic layouts that take advantage or the new smaller receivers . So air can pass by. Just seems to be an overlooked area. I think I will have to play with some lexan and other materials to better demonstrate some of the ideas as I can't draw them atm. Let's get more ideas and discussion
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Old 03-20-2014, 10:13 PM
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bitty design were testing some lexen deflectors on the mugen front top arms.

I cant remember exactly but i think it was at the dirt and neobuggy had a picture of them
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Old 03-20-2014, 11:44 PM
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That was on Carson Wernimont's Mugen.
Attached Thumbnails Aero / A-Arm Design-wernimontcf1.jpg   Aero / A-Arm Design-wernimontcf2.jpg   Aero / A-Arm Design-wernimontcf7.jpg  
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Old 03-21-2014, 12:01 AM
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There are a few of reasons why I think it hasn't been implemented on buggies with regards to aero-profiled suspension arms. Firstly, running off-road means a very uneven/inconsistent track surface, so as the suspension arm is not only moving up and down relative to the ground, but the ground itself is uneven & bumpy, so any kind of ground-effect would likely be negated by these factors.

Second, even if you managed to produce some sort of downforce from the lower suspension arms or the underside of the chassis, it would likely just throw up rooster tails of dust and debris.

Third. While buggies run on dirt/clay, they are still part airplane in that they spend a fair amount of time in the air because of jumps. Therefore, their aerodynamic needs are partially at odds with each other: you want downforce to increase grip, yet still need the buggy to jump/fly through the air controlably. I suspect that this is why the aero on the cars has always remained rather neutral.

Those are the things that just came to mind at 2am.
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Old 03-21-2014, 05:11 PM
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Originally Posted by captain america View Post
There are a few of reasons why I think it hasn't been implemented on buggies with regards to aero-profiled suspension arms. Firstly, running off-road means a very uneven/inconsistent track surface, so as the suspension arm is not only moving up and down relative to the ground, but the ground itself is uneven & bumpy, so any kind of ground-effect would likely be negated by these factors.

Second, even if you managed to produce some sort of downforce from the lower suspension arms or the underside of the chassis, it would likely just throw up rooster tails of dust and debris.

Third. While buggies run on dirt/clay, they are still part airplane in that they spend a fair amount of time in the air because of jumps. Therefore, their aerodynamic needs are partially at odds with each other: you want downforce to increase grip, yet still need the buggy to jump/fly through the air controlably. I suspect that this is why the aero on the cars has always remained rather neutral.

Those are the things that just came to mind at 2am.
All good points, while downforce may not be the ultimate objective, I still think a smoother more aero design would help. Speed, fuel ecomomy, handling Im sure, and cooling in some cases. We run big ol wings to keep the noses up in flight.. what if the car itself could do that and we could run smaller wings with less drag? Think about the size of the front side pods on some buggys. I still have to draw up my idea for a more aero shock tower, but that alone is a huge area to improve on..
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Old 03-21-2014, 05:47 PM
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Originally Posted by Stirex View Post
All good points, while downforce may not be the ultimate objective, I still think a smoother more aero design would help. Speed, fuel ecomomy, handling Im sure, and cooling in some cases. We run big ol wings to keep the noses up in flight.. what if the car itself could do that and we could run smaller wings with less drag? Think about the size of the front side pods on some buggys. I still have to draw up my idea for a more aero shock tower, but that alone is a huge area to improve on..
I'm working on something similar to that as it turns out. What you have to bear in mind is that balance is a fairly important factor, so if you decrease the size of the rear wing but your car works optimally with X amount of downforce, you need to make it up in some way, so it's like trading a dollar for four quarters in some respects. It can be a great benefit to be able to tweak the amount and location of downforce though.

With respect to drag, upright shocks, shock towers and most importantly, spiked tires are the biggest and most significant culprits. Teardrop-shaped upper links and A-arms will only claw back so much, and if you cover over the upper link enough to reduce the drag you make maintenance a problem.

A fortune cookie once proclaimed that the bestest way to go faster is to crash less.
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Old 03-21-2014, 06:11 PM
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I don't see drag being a big deal overall. We don't run these things wide open like a on road car. Down force can be important.
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Old 03-21-2014, 06:53 PM
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Originally Posted by MX304 View Post
I don't see drag being a big deal overall.
Absolutely true. Getting potentially any better fuel mileage or excess speed, from improved aerodynamics of better shaped arms or bodies on nitro buggies, is negligible at best.

Look at the millions cycling companies like Specialized and Trek spent on R&D and wind tunnel testing over last decade. Grand tour riders can push 45+km average speed into 10km headwinds for an hour. A redesigned lower drag coefficient fork/headtube may only save 2-3 seconds total time over same route with same exertion levels. Scale something like that down to RC level and it's minuscule.


While I think there's an argument to be made about improving downforce and stability in our cars - where I think we should focus - trying to improve drag won't have much result.

Another thing to keep in mind is the resources of RC companies are rather small. When's the last time you saw an RC company in a wind tunnel with some of the world's top specialists in their field of study, testing bodies? Basically all testing analysis is driver feedback (subjective), not hard factual data in test labs (objective). Companies are all too quick to sell you new things these days touting claims, with minimal proof.
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